The present invention relates to a turbine for use in a power plant using hydrogen and oxygen as the fuel. More specifically, the present invention relates to a closed loop steam cooled turbine in which steam, generated by the combustion of hydrogen and oxygen, is expanded for power generation.
A gas turbine is typically comprised of a compressor section that produces compressed air, a combustion section that transforms the compressed air into a hot, compressed gas, and a turbine section that expands the hot, compressed gas. In the combustion section, a hydrocarbon fuel, such as distillate oil or natural gas, is mixed with and burned in the compressed air in one or more combustors. Unfortunately, such combustion results in the formation of oxides of nitrogen ("NOx"), considered an atmospheric pollutant.
Combusting hydrogen in pure oxygen would eliminate all NOx formation. Combustors for rocket engines have traditionally operated by combusting liquid hydrogen in liquid oxygen. However, power turbines must operate for extended periods of time without deterioration. Consequently, the problems of cooling the combustor in a gas turbine presents challenges not present in rocket combustors. This problem is exacerbated if, for reasons of economy and ease of handling and supply, compressed oxygen gas, rather than liquid oxygen, is used. Typically, rocket combustors rely on the low temperature of liquid oxygen for cooling.
Cooling of the turbine section would also be a problem in a hydrogen/oxygen fueled power plant, especially since it is desirable to operate the turbine with inlet temperatures as high as 900 to 1600.degree. C. in order to achieve optimum power output. The air cooling traditionally used in combustion turbines negatively impacts the efficiency of the power plant.
It is, therefore, desirable to provide a system for cooling the vanes and blades of a turbine expanding steam generated by the combustion of hydrogen and oxygen.